1. Field of the Invention
The present invention relates, in general, to devices and methods for assisting a patient's heart with a cannula. More specifically, the present invention is related to devices and methods for assisting a patient's heart with a cannula where the cannula is of sufficient length to, for example, extend from the patient's internal jugular vein to the pulmonary artery.
2. Description of the Related Art
Traditional cannulae used for patient life support generally involve single lumen cannulae at multiple insertion sites, high volume circuits, and cannulae that are not capable of long-term use. Multiple insertion sites increase the risk of bleeding, vessel damage, infection, as well as pain and discomfort to the patient. These cannulae are designed and built for short-term acute therapies. Additionally, traditional cannulae usually require access sites located in the patient's groin area near the right or left femoral veins.
Patients with severe right-sided circulatory and/or right-sided ventricular failure have significantly high mortality and morbidity caused by a multitude of factors in multiple patient populations. Historically, Right Ventricular Assist Devices (RVADs) and Left Ventricular Assist Devices (LVADs) have been adapted for use on surgical patients without a percutaneous or catheter lab option available. These surgical RVADs have been applied on patients with right inferior myocardial infarction, acute right-sided ischemic myocardial infarctions (with large left and right propagation), cardiogenic shock, LVAD-created right ventricular dysfunction, post-transplant right ventricular failure, and pulmonary hypertension. Acute myocardial infarction and cardiogenic shock have been treated with intra-aortic balloon pumps and maximal inotropic support, to which many patients become refractory. Surgically implanted LVADs can create a significant septal shift that leads to a dynamic change in the Starling curve that abruptly places patients into severe right ventricular failure. Patients can limit post-transplant survival bridged to transplant to/from an RVAD with severe right ventricular failure. Secondary pulmonary hypertension leads to an exacerbation of right ventricular failure in acute and chronic situations, which may be treated with RVADs.
The foregoing conventional devices do not have the capability to reach the pulmonary artery (PA) from the internal jugular vein via a percutaneous insertion. Some traditional cannulae are inserted into the patient's heart through a direct access point in the patient's right or left femoral vein. Alternatively, traditional RVADs have a cannula either primarily placed in the PA or a graft sewn onto the PA, then a cannula inserted through the graft. The assembly can then be visualized in the PA via fluoroscopy and X-Ray with the aid of distal markers in the cannula, verifying the proper orientation of the outflow to the patient. In these embodiments, the patient's torso length can limit the ability to access the PA via percutaneous insertion. If a cannula is not of a proper length, the interventional procedure may not unload the right ventricle, which leads to an increase of morbidity and mortality.
Furthermore, traditional venoarterial extracorporeal membrane oxygenation (VA ECMO) is the current standard of care used to treat right ventricular failure and respiratory failure percutaneously. VA ECMO procedure draws blood from the right atrium and pumps it through an oxygenator and back into the arterial circulation via the femoral artery. VA ECMO bypasses the lungs and the heart completely. Therefore, residual blood is left stagnant in both the heart and lungs potentially leading to thrombosis and an inadequately unloaded right ventricle. Additionally, the arterial cannulation can lead to problems including but not limited to bleeding, stroke, and infection.